Anchored fiducial apparatus and method

ABSTRACT

An anchored fiducial apparatus is described. The fiducial apparatus anchors itself in the target region once inserted so that the fiducial apparatus does not move relative to the target region.

BACKGROUND OF THE INVENTION

[0001] This invention relates generally to an apparatus and method forlocating a particular portion of an object that is not viewable and inparticular to an apparatus and method for locating a portion of anobject by placing a marker that is viewable at or near the portion ofthe object.

[0002] In many applications, it is not possible to directly view anobject or a portion of an object that needs to be acted on in somemanner. For example, to treat a target region, such as a lung tumor,with radiation, it is not possible to be able to view the actual tumorwithin the patient immediately before the radiation treatment. It istherefore necessary to have some mechanism for permitting the lung tumorto be located accurately so that the radiation treatment can be targetedat the lung tumor while avoiding damage to healthy tissue.

[0003] In order to accurately track and target a target region, one ormore fiducials may be used. Each fiducial is typically a substance thatcan be seen when an x-ray of the patient is viewed so that the lungtumor can be effectively located and targeted. Typically, the fiducialsmay be inserted into the patient during a simple operation. Eachfiducial may be, for example, a radio-opaque substance that will bevisible during an x-ray of the patient. These typical fiducials permitmore accurate locating and targeting of the lung tumor, but there is alimit to the accuracy of targeting that can be achieved with thesetypical fiducials. In particular, the fiducials are normally placed intothe lung tumor, but are not actually anchored to the lung tumor.Therefore, over time, the fiducials may move slightly or a largedistance which makes the fiducials useless to locate the lung tumor andrequires that new fiducials be inserted into the patient. It mayactually be worse if the fiducials only move a small distance since thesurgeon may not realize that the fiducials have moved and continue thetreatment with bad targeting information (from the misaligned fiducials)that may lead to the radiation being delivered to the wrong location. Infact, the radiation may be delivered less effectively (in a smalleramount) to the lung tumor (which reduces the efficacy of the treatment)and delivered in a greater amount to the healthy tissue surrounding thelung tumor which will damage the healthy tissue and cause undesirableside effects.

[0004] To solve this problem, it is desirable to provide fiducials thatmay be anchored into a target region so that the fiducials are not ableto move away from the target region and/or migrate. Thus, it isdesirable to provide an anchored fiducial apparatus and it is to thisend that the present invention is directed.

SUMMARY OF THE INVENTION

[0005] The anchored fiducial apparatus and method in accordance with theinvention overcomes the limitations of the prior art fiducials. Inparticular, the anchored fiducials may be placed into a particularregion to provide accurate location and tracking of that region. In oneembodiment, the anchoring fiducial apparatus may be made of a radioopaque material that may be used to accurately locate a target region,such as a tumor, within a human patient during stereotaxic radiosurgery.The anchored fiducial apparatus in accordance with the invention anchorsitself when it is placed into the region (of tissue) so that theanchored fiducial does not move/change its location relative to theregion over time. The anchored fiducial apparatus may be inserted intothe region by various well known techniques wherein the anchoredfiducial is in an unanchored position during insertion into the region.Once the fiducial apparatus is inserted into the region, it may beplaced into an anchored position in a state which secures/anchors thefiducial apparatus into the region (of tissue) and therefore unlikely tomove and migrate over time as typical fiducials may.

[0006] The fiducial apparatus includes a body portion and one or moreanchoring devices that anchor the fiducial apparatus into the region. Inmore detail, each anchoring device includes an elastic member and ananchor member. In two different embodiments, the anchor members havedifferent shapes. In one embodiment, the anchor member is pyramidalshaped while in another embodiment the anchor member is an elongatedrectangularly shaped member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a diagram illustrating a first embodiment of thefiducial apparatus in accordance with the invention and a method forinserting the fiducial into a target region;

[0008]FIG. 2a is a diagram illustrating the fiducial apparatus of FIG. 1in an unanchored position;

[0009]FIG. 2b is a diagram illustrating the fiducial apparatus of FIG. 1in an anchored position;

[0010]FIG. 3a illustrates an end view of the fiducial apparatus of FIG.1 when in the unanchored position;

[0011]FIG. 3b illustrates an end view of the fiducial apparatus of FIG.1 when in the anchored position;

[0012]FIG. 4 is a diagram illustrating a second embodiment of thefiducial apparatus in accordance with the invention and a method forinserting the fiducial into a target region;

[0013]FIG. 5a illustrates the fiducial of FIG. 4 in an unanchoredposition;

[0014]FIG. 5b illustrates the fiducial of FIG. 4 in an anchoredposition;

[0015]FIG. 5c illustrates an end view of the fiducial of FIG. 4 when inthe anchored position;

[0016]FIG. 5d illustrates another view of the fiducial of FIG. 4 when inthe anchored position;

[0017]FIG. 6 is a diagram illustrating a third embodiment of thefiducial apparatus in accordance with the invention and a method forinserting the fiducial into a target region;

[0018]FIG. 7a illustrates the fiducial of FIG. 6 in an unanchored state;

[0019]FIGS. 7b and 7 c illustrate the fiducial of FIG. 6 in an anchoredstate;

[0020]FIG. 8 illustrates another embodiment of the fiducial inaccordance with the invention; and

[0021]FIGS. 9A and 9B illustrate the fiducial of FIG. 8 in an unanchoredstate and in an anchored state, respectively.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0022] The invention is particularly applicable to a fiducial apparatusfor locating a target region in a patient during surgery usingelectromagnetic radiation and it is in this context that the inventionwill be described. It will be appreciated, however, that the apparatusand method in accordance with the invention has greater utility sincethe described apparatus and method can be used to locate a portion ofany object that is not readily viewable for a variety of differentpurposes. For example, the fiducial apparatus may be used for locatingand targeting during other types of operations and medical procedures.

[0023]FIG. 1 is a diagram illustrating a preferred embodiment of thefiducial apparatus 30 in accordance with the invention and a method forinserting the fiducial into a target region. In this embodiment, thefiducial apparatus 30 may be inserted into a patient using a specificinsertion needle 32 (also known as a needle with stylet or an“introducer” that “extrudes” the fiducial). In particular, the targetregion within the patient is identified, the needle attached to asyringe is inserted into the target region and the fiducial apparatus 30is expelled from the tip of the needle as is well known. The inventionis not limited to the particular insertion method shown since thefiducial apparatus 30 may be inserted into the patient or any object byany other well known technique, such as by surgical implantation. Inthis embodiment, the fiducial apparatus may have a round cross-section(as shown in FIGS. 3a and 3 b) since it must pass through the needle ofthe syringe. However, the invention is not limited to any particularsize or shape of the fiducial apparatus as long as the fiducialapparatus is sufficiently large to be viewed on an x-ray or any othersimilar imaging apparatus. In accordance with the invention, thefiducial apparatus may be made of any material which blocks the imagingenergy so that the fiducial apparatus appears on an image generated byany typical imaging systems, such as x-rays. In a preferred embodiment,the fiducial apparatus may be made of a radio opaque material, such asgold. In other embodiments, the fiducial may be made of a material sothat it is viewable in a ultrasound image so that is may be used as aultrasound fiducial. Now, more details of the fiducial apparatus inaccordance with the invention will be described.

[0024]FIG. 2a is a diagram illustrating the fiducial apparatus 30 ofFIG. 1 in an unanchored position, FIG. 2b is a diagram illustrating thefiducial apparatus 30 of FIG. 1 in an anchored position, FIG. 3aillustrates an end view of the fiducial apparatus 30 of FIG. 1 when inthe unanchored position and FIG. 3b illustrates an end view of thefiducial apparatus 30 of FIG. 1 when in the anchored position. As shownin FIGS. 2a and 2 b, the fiducial apparatus may include a body portion34 and one or more anchoring devices 36 embedded into the body portion.In the preferred embodiment, the anchoring devices 36 are located onopposite sides of the body portion as shown in FIGS. 3a and 3 b, but theinvention is not limited to any particular orientation of the anchoringdevices 36 relative to one another.

[0025] Each anchoring device 36, in this embodiment, may include ahousing portion 38 that houses an elastic member 40, such as a spring,and an anchor member 42 attached to the elastic member 40. In thisembodiment, the anchor member is a spike that anchors itself into thetarget tissue. The spike may be pyramidal shape. The other end of theelastic member is attached to the body portion so that the elasticmember urges the anchor member 42 outwards away from the body portion.Thus, as shown in FIG. 2b, once the fiducial apparatus exits thedelivery mechanism, such as the needle of the syringe, so that thespring is no longer constrained, the anchor members 42 pop out from thebody portion and embed themselves into the target region so that thefiducial apparatus does not move/change position or migrate. FIG. 2a and3 a illustrates the anchor members in a stored position while FIGS. 2band 3 b illustrate the anchor members in an anchoring state. Thus, thefiducial apparatus is anchored into its spot such that the accuracy ofthe location of the fiducial apparatus in the target region does notchange over time as happens with typical unanchored fiducial apparatus.Now, another embodiment of the fiducial apparatus in accordance with theinvention will be described.

[0026]FIG. 4 is a diagram illustrating a second embodiment of thefiducial apparatus 30 in accordance with the invention and a method forinserting the fiducial into a target region. In this embodiment, thefiducial apparatus 30 may be inserted into a patient using a needle 32.In particular, the target region within the patient is identified, theneedle attached to a syringe is inserted into the target region and thefiducial apparatus 30 is expelled from the tip of the needle as is wellknown. The invention is not limited to the particular insertion methodshown since the fiducial apparatus 30 may be inserted into the patientor any object by any other well known technique, such as by surgicalimplantation. In this embodiment, the fiducial apparatus may have around cross-section (as shown in FIG. 5c) since it must pass through theneedle of the syringe. However, the invention is not limited to anyparticular size or shape of the fiducial apparatus as long as thefiducial apparatus is sufficiently large to be viewed on an x-ray or anyother similar imaging apparatus. In accordance with the invention, thefiducial apparatus may be made of any material which blocks the imagingenergy so that the fiducial apparatus appears on an image generated byany typical imaging systems, such as x-rays. In a preferred embodiment,the fiducial apparatus may be made of a radio opaque material, such asgold. In other embodiments, the fiducial may be made of a material sothat it is viewable in a ultrasound image so that is may be used as aultrasound fiducial. Now, more details of this embodiment of thefiducial apparatus in accordance with the invention will be described.

[0027] In particular, FIG. 5a illustrates the fiducial 30 of FIG. 4 inan unanchored position, FIG. 5b illustrates the fiducial 30 of FIG. 4 inan anchored position, FIG. 5c illustrates an end view of the fiducial 30of FIG. 4 when in the anchored position and FIG. 5d illustrates anotherview of the fiducial 30 of FIG. 4 when in the anchored position. Asshown in FIGS. 5a and 5 b, the fiducial apparatus may include a bodyportion 34 and one or more anchoring devices 36 embedded into the bodyportion. In the preferred embodiment, the anchoring devices 36 arelocated on opposite sides of the body portion as shown in FIG. 5c, butthe invention is not limited to any particular orientation of theanchoring devices 36 relative to one another.

[0028] Each anchoring device 36, in this embodiment, may include ahousing portion 50 (a trench in this embodiment) that houses an anchormember 52 and an elastic member 54, such as a spring, wherein the anchormember is attached to the elastic member. In this embodiment, the anchormember is an elongated rectangular shaped member anchored at one end sothat as it is released from the housing portion, it anchors itself intothe target region (See FIG. 5b). The other end of the elastic member isattached to the body portion so that the elastic member urges the anchormember 42 outwards away from the body portion when the anchor member isreleased. Thus, as shown in FIG. 5b, once the fiducial apparatus 30exits the delivery mechanism, such as the needle of the syringe, so thatthe elastic member is no longer constrained, the anchor members 52 popout from the body portion and embed themselves into the target region sothat the fiducial apparatus does not move/change position or migrate.FIG. 5a illustrates the anchor members in a stored position while FIGS.5b-5 d illustrate the anchor members in an anchoring state. Thus, thefiducial apparatus is anchored into its spot such that the accuracy ofthe location of the fiducial apparatus in the target region does notchange over time as happens with typical unanchored fiducial apparatus.Now, another embodiment of the fiducial apparatus will be described.

[0029]FIG. 6 is a diagram illustrating a second embodiment of thefiducial apparatus 30 in accordance with the invention and a method forinserting the fiducial into a target region. In this embodiment, thefiducial apparatus 30 may be inserted into a patient using a needle andsyringe 32. In particular, the target region within the patient isidentified, the needle of the syringe is inserted into the target regionand the fiducial apparatus 30 is expelled from the tip of the needle asis well known. The invention is not limited to the particular insertionmethod shown since the fiducial apparatus 30 may be inserted into thepatient or any object by any other well known technique, such as bysurgical implantation. In this embodiment, the fiducial apparatus mayhave a round cross-section (as shown in FIGS. 7b and 7 c) since it mustpass through the needle of the syringe. However, the invention is notlimited to any particular size or shape of the fiducial apparatus aslong as the fiducial apparatus is sufficiently large to be viewed on anx-ray or any other similar imaging apparatus. In accordance with theinvention, the fiducial apparatus may be made of any material whichblocks the imaging energy so that the fiducial apparatus appears on animage generated by any typical imaging systems, such as x-rays. In apreferred embodiment, the fiducial apparatus may be made of a radioopaque material. In other embodiments, the fiducial may be made of amaterial so that it is viewable in a ultrasound image so that is may beused as a ultrasound fiducial. Now, more details of this embodiment ofthe fiducial apparatus in accordance with the invention will bedescribed.

[0030] In particular, FIG. 7a illustrates the fiducial 30 of FIG. 6 inan unanchored state and FIGS. 7b and 7 c illustrate the fiducial 30 ofFIG. 6 in an anchored state. In this embodiment, the fiducial apparatusis made out of a memory metallic substance, such as nitinol, whichreacts to an electric field by bending as is well known. The fiducialapparatus may also be made of a material that is temperature sensitiveand bends in response to a particular temperature range, such as thetemperature within the human body. Thus, as shown in FIG. 7a, anelectric field is applied during the insertion of the fiducial apparatusso that the fiducial apparatus remains relatively straight. As shown inFIGS. 7b and 7 c, once the adjacent electric field is removed and doesnot interact with the fiducial apparatus, the fiducial apparatus bendsso that it is less likely to move within the target region.

[0031]FIG. 8 illustrates another embodiment of the fiducial apparatus 30in accordance with the invention and a method for inserting the fiducialinto a target region. In this embodiment, the fiducial apparatus 30 maybe inserted into a patient using a needle 32. In particular, the targetregion within the patient is identified, the needle is inserted into thetarget region and the fiducial apparatus 30 is expelled from the tip ofthe needle as is well known. The invention is not limited to theparticular insertion method shown since the fiducial apparatus 30 may beinserted into the patient or any object by any other well knowntechnique, such as by surgical implantation. In this embodiment, thefiducial apparatus may have a round cross-section since it must passthrough the needle of the syringe. However, the invention is not limitedto any particular size or shape of the fiducial apparatus as long as thefiducial apparatus is sufficiently large to be viewed on an x-ray or anyother similar imaging apparatus. In accordance with the invention, thefiducial apparatus may be made of any material which blocks the imagingenergy so that the fiducial apparatus appears on an image generated byany typical imaging systems, such as x-rays. In a preferred embodimentthe fiducial apparatus may be made of a radio opaque material. In otherembodiments, the fiducial may be made of a material so that it isviewable in a ultrasound image so that is may be used as a ultrasoundfiducial. Now, more details of this embodiment of the fiducial apparatusin accordance with the invention will be described.

[0032]FIGS. 9A and 9B illustrate the fiducial of FIG. 8 in an unanchoredstate and in an anchored state, respectively. In this embodiment, thefiducial apparatus may include an elastic body portion that may bestretched by the insertion of a fluid or other material into the bodyportion. As shown in FIG. 9A, when the fiducial apparatus is in theunanchored state, the body portion is empty. To put the fiducialapparatus into the anchored state, a fluid or other material 60 isinserted into the body portion 58 that expands as shown to anchor thefiducial into the target region. As with the other embodiments, thefluid may be radio opaque material or a ultrasound opaque material.

[0033] While the foregoing has been with reference to a particularembodiment of the invention, it will be appreciated by those skilled inthe art that changes in this embodiment may be made without departingfrom the principles and spirit of the invention, the scope of which isdefined by the appended claims.

1. A fiducial apparatus to be inserted into a target region, comprising:a body portion made of a material that is visible using electromagneticradiation; and one or more anchoring devices connected to the bodyportion, each anchoring device having an unanchored position and ananchored position, the unanchored position permitting the body portionto move within the target region and the anchored position anchoring thefiducial apparatus into the target region.
 2. The apparatus of claim 1,wherein the body portion further comprises a radio opaque material sothat the apparatus is viewable using electromagnetic radiation.
 3. Theapparatus of claim 1, wherein the body portion comprises a memory metalmember that bends in response to an appropriate signal to anchor itselfinto the target region.
 4. The apparatus of claim 3, wherein theappropriate signal further comprises an electric field.
 5. The apparatusof claim 3, wherein the appropriate signal further comprises apredetermined temperature.
 6. The apparatus of claim 4, wherein thememory metal further comprises nitinol.
 7. The apparatus of claim 1,wherein each anchoring device further comprises an anchor member and anelastic member connected to the anchor member that urges the anchormember into the anchored position.
 8. The apparatus of claim 7, whereinthe anchor member comprises a spike that embeds itself into the targetregion.
 9. The apparatus of claim 8, wherein the spike further comprisesa pyramidal shaped member.
 10. The apparatus of claim 7, wherein theanchor member is an elongated rectangular shaped member that embeds intothe target region.
 11. The apparatus of claim 1, wherein the targetregion comprises a target region within a human body.
 12. The apparatusof claim 11, wherein the target region further comprises a tumor in thebody of the patient.
 13. The apparatus of claim 1, wherein the bodyportion further comprises a material that is viewable using a ultrasoundimage.
 14. A method for anchoring a fiducial in a target region,comprising: inserting the fiducial into the target region, the fiducialhaving an anchoring device that anchors the fiducial into the targetregion, the anchoring device being held closed while being inserted intothe target region; and anchoring the fiducial into the target regionafter the fiducial is inserted into the target region, the anchoringdevice opening as the fiducial has been inserted into the target region.15. The method of claim 14, wherein the insertion further comprisesinjecting the fiducial into the target region using a needle.
 16. Themethod of claim 14, wherein the anchoring further comprises moving oneor more anchor devices into an anchored position in order to embed theone or more anchor devices into the target region.
 17. A fiducialapparatus, comprising: a body portion; and means for anchoring the bodyportion into the target region so that the fiducial apparatus cannotmove, each anchoring device having an unanchored position and ananchored position, the unanchored position permitting the body portionto move within the target region and the anchored position anchoring thefiducial apparatus into the target region.
 18. The apparatus of claim17, wherein the body portion further comprises a radio opaque materialso that the apparatus is viewable using electromagnetic radiation. 19.The apparatus of claim 17, wherein the body portion comprises a memorymetal member that bends in response to an appropriate signal to anchoritself into the target region.
 20. The apparatus of claim 19, whereinthe appropriate signal further comprises an electric field.
 21. Theapparatus of claim 19, wherein the appropriate signal further comprisesa predetermined temperature.
 22. The apparatus of claim 20, wherein thememory metal further comprises nitinol.
 23. The apparatus of claim 17,wherein each anchoring device further comprises an anchor member and anelastic member connected to the anchor member that urges the anchormember into the anchored position.
 24. The apparatus of claim 23,wherein the anchor member comprises a spike that embeds itself into thetarget region.
 25. The apparatus of claim 24, wherein the spike furthercomprises a pyramidal shaped member.
 26. The apparatus of claim 23,wherein the anchor member is an elongated rectangular shaped member thatembeds into the target region.
 27. The apparatus of claim 17, whereinthe target region comprises a target region within a human body.
 28. Theapparatus of claim 27, wherein the target region further comprises atumor in the body of the patient.
 29. The apparatus of claim 17, whereinthe body portion further comprises a material that is viewable using aultrasound image.